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  1. /*
  2.  * Copyright (c) 2013 Nicolas George
  3.  *
  4.  * This file is part of FFmpeg.
  5.  *
  6.  * FFmpeg is free software; you can redistribute it and/or
  7.  * modify it under the terms of the GNU Lesser General Public License
  8.  * as published by the Free Software Foundation; either
  9.  * version 2.1 of the License, or (at your option) any later version.
  10.  *
  11.  * FFmpeg is distributed in the hope that it will be useful,
  12.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14.  * GNU Lesser General Public License for more details.
  15.  *
  16.  * You should have received a copy of the GNU Lesser General Public License
  17.  * along with FFmpeg; if not, write to the Free Software Foundation, Inc.,
  18.  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19.  */
  20.  
  21. #include "libavutil/opt.h"
  22. #include "avfilter.h"
  23. #include "internal.h"
  24.  
  25. typedef struct {
  26.     const AVClass *class;
  27.     int sample_rate;
  28.     int rescale_pts;
  29. } ASetRateContext;
  30.  
  31. #define CONTEXT ASetRateContext
  32. #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
  33.  
  34. #define OPT_GENERIC(name, field, def, min, max, descr, type, deffield, ...) \
  35.     { name, descr, offsetof(CONTEXT, field), AV_OPT_TYPE_ ## type,          \
  36.       { .deffield = def }, min, max, FLAGS, __VA_ARGS__ }
  37.  
  38. #define OPT_INT(name, field, def, min, max, descr, ...) \
  39.     OPT_GENERIC(name, field, def, min, max, descr, INT, i64, __VA_ARGS__)
  40.  
  41. static const AVOption asetrate_options[] = {
  42.     OPT_INT("sample_rate", sample_rate, 44100, 1, INT_MAX, "set the sample rate"),
  43.     OPT_INT("r",           sample_rate, 44100, 1, INT_MAX, "set the sample rate"),
  44.     {NULL},
  45. };
  46.  
  47. AVFILTER_DEFINE_CLASS(asetrate);
  48.  
  49. static av_cold int query_formats(AVFilterContext *ctx)
  50. {
  51.     ASetRateContext *sr = ctx->priv;
  52.     int sample_rates[] = { sr->sample_rate, -1 };
  53.  
  54.     ff_formats_ref(ff_make_format_list(sample_rates),
  55.                    &ctx->outputs[0]->in_samplerates);
  56.     return 0;
  57. }
  58.  
  59. static av_cold int config_props(AVFilterLink *outlink)
  60. {
  61.     AVFilterContext *ctx = outlink->src;
  62.     ASetRateContext *sr = ctx->priv;
  63.     AVFilterLink *inlink = ctx->inputs[0];
  64.     AVRational intb = ctx->inputs[0]->time_base;
  65.     int inrate = inlink->sample_rate;
  66.  
  67.     if (intb.num == 1 && intb.den == inrate) {
  68.         outlink->time_base.num = 1;
  69.         outlink->time_base.den = outlink->sample_rate;
  70.     } else {
  71.         outlink->time_base = intb;
  72.         sr->rescale_pts = 1;
  73.         if (av_q2d(intb) > 1.0 / FFMAX(inrate, outlink->sample_rate))
  74.             av_log(ctx, AV_LOG_WARNING, "Time base is inaccurate\n");
  75.     }
  76.     return 0;
  77. }
  78.  
  79. static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
  80. {
  81.     AVFilterContext *ctx = inlink->dst;
  82.     ASetRateContext *sr = ctx->priv;
  83.     AVFilterLink *outlink = ctx->outputs[0];
  84.  
  85.     frame->sample_rate = outlink->sample_rate;
  86.     if (sr->rescale_pts)
  87.         frame->pts = av_rescale(frame->pts, inlink->sample_rate,
  88.                                            outlink->sample_rate);
  89.     return ff_filter_frame(outlink, frame);
  90. }
  91.  
  92. static const AVFilterPad asetrate_inputs[] = {
  93.     {
  94.         .name         = "default",
  95.         .type         = AVMEDIA_TYPE_AUDIO,
  96.         .filter_frame = filter_frame,
  97.     },
  98.     { NULL }
  99. };
  100.  
  101. static const AVFilterPad asetrate_outputs[] = {
  102.     {
  103.         .name         = "default",
  104.         .type         = AVMEDIA_TYPE_AUDIO,
  105.         .config_props = config_props,
  106.     },
  107.     { NULL }
  108. };
  109.  
  110. AVFilter avfilter_af_asetrate = {
  111.     .name          = "asetrate",
  112.     .description   = NULL_IF_CONFIG_SMALL("Change the sample rate without "
  113.                                           "altering the data."),
  114.     .query_formats = query_formats,
  115.     .priv_size     = sizeof(ASetRateContext),
  116.     .inputs        = asetrate_inputs,
  117.     .outputs       = asetrate_outputs,
  118.     .priv_class    = &asetrate_class,
  119. };
  120.